The present invention relates to apparatus for monotoring the extent of recurrent movement of a driven part through a predetermined portion of its path which the driven part may but need not traverse after a second part has moved through a predetermined distance. More particularly, the invention relates to apparatus which can ascertain the extent of angular displacement of a rotary second part from a first or zero position to a second position, wherein the extent of such angular displacement may be less than, equal to or in excess of 360 degrees and wherein the second position is reached when the monitored part traverses the predetermined portion. Still more particularly, the invention relates to improvements in apparatus which can be utilized with advantage to monitor the deviations (if any) of the path of a shuttle in a loom from the standard throw traversed by the shuttle.
Swiss Pat. No. 557,561 to Lopfe discloses an apparatus wherein the determination traversed by deviations of path of the shuttle from standard throw necessitates the measurement of angular velocity of a rotary member, namely, a shaft of the loom. The apparatus ascertains the interval which elapses between the instant of movement of the shaft through a predetermined angular position and the instant of travel of the shuttle in a predetermined portion of its path. The just described monitoring system is complex and the determination of deviations is time-consuming because the interval must be ascertained by calculation. The fact that the angular velocity of the shaft need not be constant also contributes to complexity of the monitoring operation.
Commonly owned Swiss Pat. Nos. 541,808 and 557,542 disclose apparatus for stroboscopically monitoring the deviations of the timing or path of a shuttle from standard throw. Such apparatus exhibit the drawback that the optical system which is incorporated therein is complex, expensive and prone to malfunction.
Certain other apparatus which disclose monitoring means serving a purpose similar to that of the aforementioned Swiss patents are disclosed in U.S. Pat. Nos. 2,670,014 to Hutchinson and 3,326,246 to Gurney, in Swiss Pat. No. 578,634 to Hanel, in French Pat. No. 2,311,874 to Nissan Motor Company, Ltd., and in German Printed Publications Nos. 2,264,779 to Suzuki, 2,543,045 to Kakinaka and 2,063,810 to Wesseler.